The present invention relates generally to gas turbine engine exhaust nozzles, and, more particularly, to an exhaust nozzle having an improved exhaust nozzle flap seal.
One type of conventional gas turbine engine exhaust nozzle includes primary and secondary exhaust flaps arranged for defining a variable area converging-diverging exhaust nozzle. The exhaust nozzle is axisymmetric, or annular, and exhaust flow is confined by the primary and secondary flaps being positioned circumferentially adjacent to each other, respectively.
The secondary flaps, for example, have a forward end defining a throat of minimum flow area and an aft end having a larger flow area for defining a diverging nozzle extending downstream from the throat. The secondary flaps are variable, which means that the spacing between the secondary flaps as they are moved from a smaller radius position to a larger radius position must necessarily increase. Accordingly, conventional exhaust nozzle flap seals are suitably secured between adjacent ones of the secondary flaps to confine the exhaust flow and prevent leakage of exhaust flow between the secondary flaps.
In an advanced axisymmetric exhaust nozzle configured for obtaining thrust vectoring, the secondary flaps are positionable not only symmetrically relative to a longitudinal centerline of the exhaust nozzle, but may be positioned asymmetrically relative thereto for obtaining pitch and yaw vectoring. In such a position, adjacent secondary flaps are positioned askew from each other, and therefore the exhaust nozzle flap seal disposed therebetween must be effective for maintaining sealing also as the secondary flaps are positioned for vectoring.
Furthermore, since the exhaust nozzle is channeling relatively hot combustor discharge gases, the exhaust nozzle flap seals must be able to accommodate such relatively hot temperatures and differential movement of structural elements due to differential heating and cooling thereof.